Zooplankton variability in the Zuari estuary, Goa

Abstract

Short term variability in the secondary production and composition of zooplankton were studied during February to March 1979 by collecting zooplankton every alternate day from a station located near the mouth of Zuari. Irregularity in the production was found to be a characteristic feature. Rate of zooplankton production fluctuated from 52 to 1388 mg C/100 m@u3@@ / day. A total of six peaks in zooplankton biomass were observed and the time lag between two peaks was 7 to 14 days. High values of zooplankton biomass were associated with high tide. Distribution of various groups of zooplankton indicated variability in their quantitative and qualitative representation. Most common groups like copepods, decapods and chaetognaths followed a pattern similar to that of the biomass. @iLucifer hanseni@@ formed an appreciable part of the total decapod population. @iAcetes indicus@@ and penaeid larvae were more common in February. Congregations of cirripede nauplii appeared thrice during the period of investigation. @iSagitta bedoti@@ dominated the samples till middle of March and later @iS. enflata@@ became the most abundant species. Groups like ctenophores, polychaetes, gastropods and cladocerans occasionally appeared in patches. It would appear that spatial heterogeneity in zooplankton population can be better explained by more frequent sampling